Project Summary/Abstract The candidate for this award seeks further mentored research experience while developing career skills to facilitate a successful transition to research independence. Therefore, she has proposed additional experimental and professional training during her postdoctoral fellowship in the lab of Dr. Toren Finkel at the NHLBI. She will take advantage of the outstanding scientific environment in her mentor's lab and at the NHLBI to learn new techniques, including proteomics, RNA sequencing, bioinformatics and computational analysis, and animal work including advanced phenotyping tests. To train her in these methods and assist her in her research aims, she has established collaborations with Dr. Elizabeth Murphy's lab and several NHLBI core facilities. Furthermore, the candidate has designed a career development plan to ensure she prepares thoroughly for an academic position by cultivating her oral and written communication, mentorship, and lab management skills. The candidate has assembled an advisory committee consisting of her primary mentor and several other scientists who not only have extensive scientific experience in fields related to the mitochondrial biology proposed in this grant, but also have committed to guiding her on presentations, job applications, and negotiation strategies. This training will help the candidate secure a tenure-track position in academia. The research goal of this proposal is to dissect the molecular mechanism and physiological role of mitochondrial calcium regulation. Mitochondrial uptake of calcium can help to stimulate ATP production, but too much calcium can lead to opening of the mitochondrial permeability transition pore, triggering cell death. The selective channel through which calcium can rapidly enter the mitochondria, the mitochondrial calcium uniporter, is a multi-protein complex whose components are beginning to be identified. EMRE and MICU1 are two of these proteins that in cell lines have been shown to play critical roles in regulation of calcium uptake. The candidate has generated the first mouse models of EMRE and MICU1 deletion to elucidate the in vivo role of mitochondrial calcium. Her recent publication showed that MICU1 deletion leads to mitochondrial calcium overload, leading to drastically decreased survival and other defects. She will next characterize the effect of EMRE deletion on the molecular architecture of the uniporter as well as on organismal physiology (Aim 1). Her preliminary data suggest that without EMRE, mitochondria cannot uptake calcium. Therefore, the candidate will use MICU1 and EMRE deletion as genetic reagents representing ?gain? and ?loss? of function in terms of mitochondrial calcium uptake to elucidate how mitochondrial calcium regulation alters in vivo physiological function in global gene expression, aging, and disease (Aim 2). A number of muscular and neurodegenerative diseases have long been associated with mitochondrial calcium overload, but the generation of these mouse models will enable the first direct tests of the impact of mitochondrial calcium on organismal physiology. The completion of these aims thus is of both basic and clinical importance.